Thanks for the link, Frank. Nicely put: “comparing notes” to instruct oneself and deepen one’s own faith. Not to persuade another to make a change.
The problem might be with the assumption that it has to be an argument, rather than a discussion. There have in the past been several interfaith dialogues and discussions—my shelves are full of such books, especially of the Buddhist-Christian dialogue—as well as a few ecumenical conferences of note.